1. Field of the Invention
The present invention relates to a new and improved fully automated machine or apparatus for automatically manufacturing or "cutting" gears, especially longitudinally curved tooth gears and to a method of operating such gear manufacturing or "cutting" machine or apparatus for the fabrication of gears, particularly bevel and hypoid gears.
Generally speaking, the gear manufacturing machine of the present development for automatically manufacturing longitudinally curved tooth gears according to a forming or generating process, is of the type wherein through integration or operative coaction of controlled and regulated drives, an electronic transmission or gear box and a control computer, there can be controlled machine axes and machine spindles during both machine set-up and machine operation. In particular, the inventive gear manufacturing machine comprises a machine base or bed and a pivotable table mounted at the machine base and pivotable about a predetermined pivot axis. This pivotable table is provided with a headstock or support mounted at the pivotable table for radial displacement with respect to the predetermined pivot axis. This headstock is provided with a workpiece or work spindle having a predetermined workpiece spindle axis or work axis. A generating stock or support is arranged at the machine base. A generating drum is mounted at the generating stock or support. The generating drum is rotatable about a generating axis or tool axis. A tool spindle is mounted at the generating drum for rotation about a predetermined tool spindle axis. Furthermore, there are provided means for shifting or displacing the generating stock or the pivotable table relative to one another along the generating axis.
2. Discussion of the Background and Material Information
Modern day gear manufacturing or generating machines enable fully automated gear manufacture by removal of stock or material from a workpiece using end cutter heads while employing a continuous indexing method or intermittent indexing method. It is also possible to use suitable grinding tools.
Such type of gear manufacturing or cutting machine has been disclosed in European Published Patent Application No. 0,355,318, published Feb. 28, 1990 and the cognate U.S. Pat. No. 4,930,950, granted Jun. 5, 1990. A motor-driven generating drum rotatably mounted in a generating stock additionally contains, however, three further setting drums, each of which are rotatably mounted. Specifically, such three further setting drums comprise an eccentric drum, an orientation drum and an inclination drum. Prior to performing the gear cutting operation, these setting drums must be setup in such a manner that the cutter head which has been mounted for rotation at such drums, as the tool assumes a proper or desired position for cutting a gear. Apart from this, it is necessary to additionally set the pivotable table about the vertical pivot axis, the workpiece headstock radially with respect to the pivot axis and, additionally, a vertically displaceable carriage or slide (the hypoid stock or support) All of these machine settings are automatically setup and locked in position by means of an electronic control device Both the machine setup work and the gear cutting operation are automatically performed by a diskette or other suitable data carrier inserted into the electronic control device. The three additional drums required for the inclination of the cutter head, however, result in complex, expensive solutions which are associated with problems of rigidity of the gear cutting machine.
German Published Patent Application No. 3,643,967, published Jul. 2, 1987 and International PCT Application No. PCT/US87/02083, filed Aug. 24, 1987 and published as International Publication No. WO 89/01838 on Mar. 9, 1989, teach gear generating machines serving the same purpose. These gear generating machines use fewer movable machine axes and, in particular, do not use any generating drum. There are provided three mutually orthogonally arranged machine axes, a pivot axis and two machine spindles. The generating motion is produced by at least two of the orthogonal axes and the offset of the axes (hypoid arrangement of non-intersecting axes) is produced by at least one of the orthogonal axes. Furthermore, there is not provided any inclination device or tilting facility for the cutter head spindle Automation of all of the operations is accomplished by control means and appropriately regulated drive means for these machine axes and spindles. There thus can be realized all gear cutting operations and setting possibilities of conventional gear cutting or manufacturing machines and are assumed to be known, especially also the kinematic equivalent of inclining or tilting the cutter head as well as correction of the longitudinal form of the tooth flanks, with single flank cutting, double flank cutting and so forth. However, during the gear generating operation, kinematic stability problems arise due to the arrangement of the axes as well as by virtue of the resultant pronounced non-linear motion patterns.
Older conventional gear manufacturing or cutting machines are known in this technology wherein the workpiece spindle is driven in synchronism with the tool spindle and the generating movement is accomplished by gear trains. A control mechanism controls the rapid traverse and forward feed of a generating stock during the operating phases. A generating drum is mounted at the generating stock. A transverse carriage or slide is additionally arranged at the generating drum and a tool spindle is mounted, if desired, for limited pivotable movement, for instance, through an angle of about 3.degree., at the transverse carriage or slide. Furthermore, a vertically displaceable hypoid carriage or slide is additionally arranged at the workpiece headstock and is mounted to be manually shiftable upon the pivotable pivot table. All of the machine axes, apart from the two rotary spindles, the generating stock and the generating drum, can be manually set and subsequently locked in place. However, these machines no longer comply with present day production requirements.